base Add action completion

[outis]

Have you ever been too lazy to type out "dependents" as an action? Ever wish you could type "port b" to build a port and leave it at that? Wait no more, for action completion is now here.

The attached patch allows a user to specify the prefix of an action name rather than the full action name. If the given prefix is ambiguous (i.e. it's the prefix for more than one action), port informs the user which actions matches the prefix and does no further processing for that action. If no action matches, port informs the user the action is unrecognized (as it does currently).

Examples:

  port ec leaves # equivalent to `port echo leaves`
  port ve         # equivalent to `port version`
  port h        # equivalent to `port help`
  port i gawk # ambiguous: could be "install", "inactive", "info" or "installed"

The new behavior could use some testing, though I don't think it will cause any problems.

[outis]

adds action completion

[jmroot (Joshua Root)]

r79259